Pathogenic viruses can be classified into two general types with respect to the viral structure, i.e., those that contain lipids and those that do not. Some well-known lipid-containing pathogenic viruses, known as “enveloped” viruses, include herpes virus, e.g., Herpes simplex 1 and 2; myxovirus, e.g., influenza virus; paramyxovirus, e.g., virus responsible for measles and mumps, and respiratory syncytial virus responsible for croup; corona virus, which is also implicated in the common cold; and toga virus, e.g., rubella virus and virus responsible for encephalitis and hemorrhagic fever. Many other pathogenic viruses lack an outer envelope, and therefore are characterized as “naked” viruses. Included in this category are the rhinovirus (the principle causative agent of the “common cold”), influenza viruses, polioviruses, and adenoviruses.
Viral infections cause considerable discomfort, disease and can be fatal. Viruses such as cytomegalovirus (CMV), human lymphotrophic viruses (e.g., HTLV-1) and human immunodeficiency viruses (e.g., HIV-1) result in significant morbidity and mortality. Herpes simplex viruses (HSV-1 and HSV-2) are associated with inflammation and lesions of the skin and mucosal membranes, including cold sores, fever blisters and genital herpes lesions. Varicella-zoster virus (VZV) causes chicken pox and shingles, and Epstein-Barr, virus (EBV) is associated with mononucleosis. Influenza viruses cause flu symptoms and can be fatal. HIV causes acquired immunodeficiency, which debilitates and kills infected individuals. Although these viruses may remain latent in some cells and for varying periods of time, generally viral replication results in irreversible destruction of the infected cell producing different clinical manifestations of the diseases they cause.
Herpes simplex infections occur and recur at many areas and organs of the body, but particularly the skin and muco-cutaneous areas. Roughly 50 million Americans suffer from fever blisters or cold sores with more than 100 million episodes estimated annually. The medical term for the condition is recurrent Herpes simplex labialis. It is caused by the Herpes simplex virus (HSV) which, following a primary infection, takes up permanent life-long residence and lies dormant in the nerve ganglia. Upon reactivation by various stimuli, the virus travels along nerve pathways towards the lips and mouth where it emerges as a lesion or blister. Disfiguring lesions typically last 7 to 10 days. Other common sites for outbreaks caused by HSV include anywhere on the skin such as the ears, nose, chest, abdomen, arms, palms, dorsa of the hands, fingers, thighs and legs. Other common sites are the eyes and cervix. Less often involved but observed are the mouth, respiratory tract and central nervous system.
The “common cold” is a phrase used by both physicians and lay persons alike for the identification of acute minor respiratory illness. Since the identification of rhinovirus in 1956, a considerable body of knowledge has been acquired on the etiology and epidemiology of common colds. It is known that the common cold is not a single entity, but rather is a group of diseases caused by members of several families of viruses, including parainfluenza viruses, rhinoviruses, respiratory syncytial viruses, enteroviruses, and coronaviruses. Much work has been performed in characterizing viruses that cause the common cold. In addition, the molecular biology of rhinoviruses, the most important common cold viruses, is understood in great detail. In contrast, progress on the treatment of common colds has been slow despite these advances. While there are now large numbers of compounds that have been found to exhibit antiviral activity against cold viruses in cell culture, many antiviral compounds have had limited effectiveness in patients.
Because of the widespread dissatisfaction with the currently marketed treatments for the common cold and allergic rhinitis within the affected population, there exists a need for a more efficacious and safe treatment. The present invention provides such a treatment.
It is known in the art that quaternary ammonium compounds such as benzalkonium chloride are effective against bacteria but are not virucidal. In Hendley et al., (Antimicrobial Agents and Chemotherapy, 14:690-694 (1978)) foams containing ethyl alcohol, benzalkonium chloride (BAK), and hexachlorophene were evaluated. Ethyl alcohol alone was not effective, and the combination of ethyl alcohol with BAK was fairly ineffective in killing rhinoviruses.
It is known in the art that “enveloped” viruses are relatively sensitive and, thus, can be inactivated by virucidal disinfectants known so far. In contrast, greater problems are caused by naked viruses, which are substantially more stable against conventional disinfectants and which can be inactivated only with relatively high concentrations of formaldehyde. However, formaldehyde is undesirable because of toxicity and does not allow the disinfection of contaminated parts of the body to be effected in either the clinic or the laboratory.
Poli, et al. (Food Chem. (England) 4(4):251-258 (1979>> describe a study of the virucidal action of organic acids (citric, malic, etc.). These workers found that citric, malic, pyruvic and succinic acids, among others, were effective in vitro against “enveloped” viruses (herpesvirus, orthomyxovirus and rhabdovirus (Rabies virus)). Their experiments were carried out at room temperature with aqueous solutions of pure acids. No substrate or carrier was used. The three viruses chosen for study by these workers were all “enveloped” viruses. Poli, et al. also observed that these acids were not effective against adenovirus, which is a “naked” virus. Based on this, they concluded that these acids were effective in vitro against “enveloped” viruses but not against “naked” viruses. In vivo, an acid solution would not work, as it is unable to penetrate the outer dermal layer and so cannot get to the virus where it is replicating.
The use of certain alcohols (i.e., alcohols of certain chain lengths) to inactivate lipid-containing viruses is disclosed by W. Snipes, et al. (Antimicrobial Agents and Chemotherapy, 11(1): 98-104, (1977)). Although the authors used alcohols ranging from C4 to C18, they point out that a striking peak in virucidal activity was found for saturated alcohols having chain lengths from ten to fourteen carbons. Since longer-chain alcohols having ten carbons or more are extremely insoluble in aqueous media, the preferred C10-C14 alcohols first had to be prepared in 95% ethanol at 100 times the desired final concentration. The final treatment was in solutions adjusted to a pH of at least 7.2. Thus, although the C10 to C14 alcohols were shown to have good virucidal action, their relatively low water solubility is a disadvantage in view of the initial preparation steps required.
Konowalchuk et al. reported a 1000-fold reduction in poliovirus infectivity after incubation with grape juice, at the natural pH of the wine (pH 3.3-4.4) or at pH 7.0 for 24 hours at 4° C., and found that commercial grape juice at neutral pH inactivated the Herpes simplex virus. Red wines were reported to be more antiviral than white wines. The effect of wine at its natural pH against the Herpes simplex virus was not examined.
Noda et al. (1981) Jap. Ass. Infect. Dis. 55: 355-366) have reported that pure methanol, ethanol, n-propanol, isopropanol or butanol have distinct but limited virucidal effects in vitro in very high concentrations of around 80% or more. Lower concentrations of these alcohols were not sufficiently effective. Individually, pure propanol, isopropanol, or various butanols were not sufficiently active against “naked” hydrophilic viruses. Known mixtures of ethanol and isopropanol with a total active-substance content of 20 to 40% also show no virucidal activity.
Von Rheinbaben et al. (U.S. Pat. No. 5,728,404) disclose compositions having virucidal activity against “naked” viruses (e.g., polio, adeno, vaccina, and SV40 tumor virus) comprising 50% to 90% by weight of at least one member selected from the group consisting of C1 to C4 aliphatic monohydric alcohols and from 0.1% to 1.0% by weight of at least one metal salt, such as a zinc salt. Von Rheinbaben et al. found that compositions comprising between 40-80% by weight of ethanol, n-propanol, isopropanol, butanol, or mixtures thereof that were ineffective against polio, adeno, vaccinia, and SV40 tumor viruses; however, these compositions could be made virucidal by adding metal salts to these alcoholic compositions.
Revici et al. (U.S. Pat. No. 4,513,008) disclose a method of inactivating an enveloped virus (HSV-2) which comprises contacting the virus with a virucidally effective amount of a C20 to C24 linear polyunsaturated acid, aldehyde or primary alcohol having 5-7 double bonds.
Brown-Skrobot et al. (U.S. Pat. No. 4,975,217) disclose a composition having germicidal activity when applied to hands contaminated with Serritia marcescens, a gram-negative bacteria, wherein the composition consists essentially of an anionic surfactant (e.g., an alkyl sulfonate salt) and an organic acid (malic acid, citric acid, and mixtures thereof). Brown-Skrobot et al. state that the surfactant alone and the acid alone showed no germicidal activity, and emphasize that both the organic acid and the anionic surfactant must be used to achieve significant germicidal activity. Alcohol was mentioned as an optional v ingredient in the Brown-Skrobot et al. composition. However, Brown-Skrobot et al. did not test the effectiveness of this composition against viruses.
Homer, et al. (U.S. Pat. No. 5,043,357) disclose compositions having virucidal activity against naked viruses (e.g., poliovirus type 1), having at least 70% by weight of ethanol and/or propanols and from 0.5% to 5% by weight of a short-chain acid. Ethanol and propanol alone did not exhibit sufficient activities against the naked viruses. These compositions were not tested for their effectiveness against enveloped viruses, nor were the virucidal activities of the compositions tested in vivo.
Hendley et al. (U.S. Pat. No. 6,034,133) disclose a hand lotion effective against the naked rhinovirus, containing malic acid, citric acid, and a C1 to C6 alcohol for preventing hand-to-hand transmission to rhinoviruses. Hendly et al. state that the lotions retain their virucidal activity as long as the concentration of the alcohol in the lotion is between 25-90%. The pH of the lotion is adjusted to be between pH 3 and pH 6 to avoid irritating the skin.
Dove et al. (U.S. Pat. No. 5,071,650) disclose an in vitro method of inactivating viruses such as VSV (a lipid-coated virus) present in a aqueous solution of biologically active protein (e.g., plasma or cell cultures) by treating the solution with an intermediate length alcohols (C4 to C10) at a pH of about 4 to 5 at a temperature of 4° C., with virucidal activity increasing with increasing carbon chain length up to C8. Ethanol and butanol were found to be fairly inactive under these conditions.
Recently, the FDA has approved docosanol (10% cream) as a treatment for recurrent oral-facial herpes (cold sores and fever blisters) (see Katz et al. U.S. Pat. Nos. 5,952,392 and 5,534,554). Because of the low water solubility of this long chain (C26) alcohol, the composition requires a bifunctional block-polymer nonionic surfactant in order to produce a suspension or emulsion of the docosanol. Further, U.S. Pat. No. 5,534,554, states that certain excipients were detrimental to the activity of n-docosanol, and stress that the preparation of stable, effective n-docosanol-containing compositions presented an unexpectedly difficult challenge.
A need continues to exist for topical compositions that are active against enveloped and naked viruses and have very low toxicity. In particular, there is a need for topical virucidal compositions that are effective against viruses of the Herpesviridae and Poxviridae families that are inexpensive and easy to use.